Directional difference filter: Its effectiveness in the postprocessing of noise detectors

In this paper, we propose a directional difference filter that possesses su perior noise removal for images corrupted by additive impulse noise and a h igh level of original signal preservation. By estimating the pixel value of the processing point from directional shape information about the edges an d successively updating the estimate, the proposed filter can prevent resid ual noise even when impulse noise generated at a high probability was added . In addition, this process can perform original signal preservation robust to the detection errors of the noise detector and is extremely useful as a postprocess for a noise detector that is used to remove noise generated at a high probability. In this paper, we demonstrate the robustness of the pr oposed method to the detection errors generated when using an actual noise detector and use processing examples to verify the superior image processin g results over conventional noise removal filters. (C) 2001 Scripta Technic a, Electron Comm Jpn Pt 3, 85(2): 74-82, 2002.